This invention relates to the physical property measuring arts, and, more particularly, to means for ascertaining the specific gravity of a gas.
There are many applications in which it is highly desirable to have means for easily and accurately determining the specific gravity of a gas. The term specific gravity defines the ratio of a density of any gas to the density of air where both gases are examined at standard conditions such as temperature and pressure. The instrument that measures specific gravity is referred to as a gravitometer. The instrument that measures the density of a gas under flowing stream conditions is usually referred to as a densitometer. There are at present both densitometers and gravitometers available on the market, and these instruments are being used under conditions of high volume flow which is necessary to justify them economically since they are very expensive.
In one specific application, the rapidly increasing cost of natural gas has inclined the industry to sell natural gas on the basis of its energy or caloric content. This approach requires a knowledge of the specific gravity of the natural gas as well as the constituents of the gas. The present invention finds particular use in such an application and comprises a method which is easily practiced with relatively inexpensive apparatus in a total gas measurement system.
It is therefore a broad object of my invention to provide improved means for measuring the specific gravity of a gas.
It is another object of my invention to provide such means which are simple and economical to practice.
In a more specific aspect, it is an object of my invention to provide a gas density measuring method in which the pulse repetition rate of an astable fluidic oscillator through which the sample gas is flowing is measured and related to the pulse repetition rate of the same or a like fluidic oscillator through which air, at like temperature and pressure, flows.